<header>
  <div class="container">
    <div class="logo">
      <img src="../../../assets/images/logo2.png" alt="logo" />
    </div>
    <div class="user">
      <a *ngIf="!user; else context">登录</a>
      <ng-template #context>
        张三
        <a>退出</a>
      </ng-template>
    </div>
  </div>
</header>
